Meant to post this on my reply to pete, but me hand slipped.
Forgot to say, that a geophysical survey found a 6 ring concentric timber circle few years back (you all probably know this anyway) at Stanton Drew's large circle, with a large 'Henge like' earth bank running around the outside oriented NE. I was gonna add soething else too, but i've just gone blank ;( doh!